Apparatuses and methods for interstitial tissue removal

ABSTRACT

Apparatuses and methods for removing solid tissue from beneath a tissue surface are described. The methods rely on positioning an energy conductive element at a target site beneath the tissue surface and energizing the element so that it can vaporize tissue. The element is then moved in a pattern which provides the desired tissue removal geometry, such as spherical, ovoid, or cylindrical. Usually, the shaft is moved, typically rotated or reciprocated, and the energy conductive element is moved relative to the shaft, typically by pivoting a rigid element or bowing a flexible element.

CROSS-REFERENCES TO RELATED APPLICATIONS

[0001] This patent application is a division of application Ser. No.09/930,531 (Attorney Docket No. 019188-000120), filed on Aug. 14, 2001,which was a division of application Ser. No. 09/249,208 (Attorney DocketNo. 019188-000110), filed on Feb. 12, 1999, (now U.S. Pat. No.6,296,639), which claimed the benefit under 35 USC 119(e) of provisionalapplication No. 60/092,572, filed on Jul. 13, 1998, the full disclosuresof which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates generally to medical devices, kits,and methods. More particularly, the present invention relates toapparatuses and methods for removing tissue from tissue regions beneatha tissue surface.

[0004] The removal of diseased and other tissues is the basis for manysurgical procedures and is accomplished in many different ways. Mostcommonly, the target tissue is excised using a cutting blade, such as ascalpel, in open surgical procedures. Typically, the cutting blade isadvanced into a tissue through an exposed tissue surface, and the targettissue is simply cut out and removed. While very effective for tissueremoval at or near an exposed tissue surface, this approach is lesseffective for tissue removal from sites spaced below the closest exposedtissue surface.

[0005] For removal of target tissue below a tissue surface, a surgeoncan simply cut down to the level of the target tissue and cut out andremove the tissue at that level. The need to cut down through“non-target” tissue is, however, disadvantageous in several respects.First, surgically cutting through the overlying healthy tissue cancreate a much bigger incision than is necessary for simply removing thetarget tissue. Moreover, the need to penetrate through relatively thicklayers of overlying tissue can complicate identification of the targetregion, often requiring that larger volumes of tissue be removed toassure to complete removal. Additionally, the ability to cut down intointernal organs during minimally invasive endoscopic procedures issignificantly more limited than in open surgical procedures.

[0006] Surgical instruments for removing tissue beneath a tissue surfacehave been developed. For example, instruments employing specializedcutting blades for chopping or “morcellating” tissue into small piecesand aspirating the resulting debris have been developed. While suchinstruments are at least theoretically capable of being manipulated toremove a defined volume of tissue beneath a tissue surface, theirperformance suffers in various ways. Most importantly, tissuemorcellation can result in significant bleeding which is difficult tostaunch. Thus, these techniques would not be useful in highlyvascularized tissues, such as many muscle and organ tissues. Even whencombined with electrosurgical coagulation, such tissue morcellationdevices are probably not useful for the removal of large tissue volumesbeneath a tissue surface where bleeding control is problematic.

[0007] For all of these reasons, it would be desirable to provideimproved apparatuses and methods for tissue removal beneath tissuesurfaces. In particular, the devices and methods should be suitable foruse in minimally invasive procedures, such as procedures where thedevices are introduced through a port and viewed under endoscopicviewing. The methods and devices should further allow access to a targettissue region with minimum disruption and damage to the overlying“non-target” tissue. Additionally, it would be desirable to providetissue removal regions with a simplified approach for removing thedebris resulting from the tissue removal. It would be particularlydesirable to provide such tissue removal methods and devices whichresult in minimum or easily controlled bleeding at the tissue removalsite. Such methods and apparatuses should still further provide forremoval of controlled volumes, even relatively large volumes of at least0.5 cm³, preferably at least 50 cm³, and still more preferably at least500 cm³, or more. The methods and apparatuses should also be useful on awide variety of tissue types and for a wide variety of specificprocedures. At least some of these objectives will be met by theinvention described hereinafter.

[0008] 2. Description of the Background Art

[0009] A loop electrode for radiofrequency electrosurgical excision of atissue volume in solid tissue is described in Lorentzen et al. (1996)Min. Invas. Ther. & Allied Tecnol. 5:511-516.

[0010] Three-dimensional electrode arrays for deployment in solid tissuefollowed by the application of radiofrequency energy to necrose tissuevolumes are described in U.S. Pat. Nos. 5,827,276; 5,735,847; and5,728,143.

[0011] Atherectomy catheters having radially expansible blade structuresintended for rotational stenotic excision in blood vessels are describedin U.S. Pat. Nos. 5,556,408; 5,554,163; 5,527,326; 5,318,576; 5,100,423;and 5,030,201. In particular, U.S. Pat. No. 5,554,163, describes acatheter having a flexible “cutting” element that may be radiallydeployed from the catheter body. U.S. Pat. No. 5,100,423, describes acutting structure comprising a plurality of helically-shaped cuttingwires that can be connected to an electrosurgical power supply to effectcutting of obstructing matter in a blood vessel. The following patentsdescribe other electrosurgical instruments: U.S. Pat. Nos. 2,022,065;4,660,571; 5,217,458; 5,578,007; 5,702,390; 5,715,817; 5,730,704;5,738,683; and 5,782,828.

BRIEF SUMMARY OF THE INVENTION

[0012] The present invention provides improved methods, devices, andkits for removing tissue from internal target sites disposed beneath atissue surface. The present invention can provide a number of advantageswhen compared to prior tissue removal techniques, including minimizingdisruption of the tissue overlying the target site, i.e., between thetissue surface and an outer periphery of the target volume which is tobe removed. In the preferred examples described below, access throughthe overlying tissue can be achieved with a single percutaneous ortranscutaneous tissue tract sufficient to accommodate a single shaft ofthe apparatus. In addition to minimizing disruption of overlying tissue,the present invention can significantly reduce bleeding at the targetsite after tissue removal. In particular, by employing electrocautery aspart of the tissue excision process, bleeding of the surrounding tissuescan be substantially staunched. Other advantages provided by the presentinvention include the ability to remove relatively large tissue volumes,typically, at least 0.5 cm³, often at least 50 cm³, and sometimes aslarge as 500 cm³, or larger. While the present invention is particularlysuited for removing large volumes. The tissue removal can be effected inmany tissue types, including those specifically set forth below, andtissue debris remaining after removal can be transported from the site,typically through the single access tract described above, usually byaspirating vapors and cellular debris which are produced as the tissueexcision and vaporization stages occur. In addition or as an alternativeto vapor aspiration, the tissue void which is being created mayoptionally be flushed with a suitable liquid or gas, preferably anelectrically non-conductive liquid, such as sorbitol. Furtheroptionally, the flushing medium may carry medications or otherbiologically active substances, such as antibiotics, pain killers,hemostatic agents, and the like. Such flushing may occur concurrentlywith the cutting, during brief periods when cutting is ceased, and/orafter all cutting has been completed.

[0013] The present invention is suitable for removing defined volumes oftissue from a variety of different tissue types, including breasttissue, liver tissue, kidney tissue, prostate 5 tissue, lung, uterine,and the like. Thus, the tissue surface may be on the patient's skin,e.g., in the case of breast tissue removal, or the tissue surface may belocated subcutaneously, e.g., in the case of internal body organs. Inthe former case, access to the target site may be achievedtranscutaneously or subcutaneously, where the removal device penetratesdirectly through the skin. In the latter case, a secondary procedure isneeded to access the tissue surface of the internal body organ. Thesecondary procedure may be an open surgical procedure where theoverlying skin and body structures are surgically opened. Alternatively,the secondary procedure may itself be minimally invasive where smallincisions or ports are used to introduce the devices of the presentinvention together with any necessary or useful auxiliary devices forperforming the tissue removal. Typically, such minimally invasivesurgeries will be performed under endoscopic visualization where thetreating physician views the procedure on a video screen. As a stillfurther alternative, access to internal body organs may be achievedintraluminally, preferably endoscopically. Typically, such intraluminal,endoscopic access will be obtained through body lumens having naturalorifices, such as the esophagus, colon, uterus, fallopian tubes,sinuses, uterus, ureter, and urethra. Such access will typically beachieved using a flexible catheter which can provide a platform foradvancing the energy conductive elements, as described in more detailbelow.

[0014] The depth of the target site will depend on the nature of thetissue and the nature of the disease or other condition being treated.Typically, the closest periphery of the target site will be locatedbetween the adjacent or available tissue surface by distance in therange from 0.5 cm to 15 cm, usually from 5 cm to 7 cm. The volume oftissue to be removed will typically be in the range from 0.5 cm³ to 500cm³, typically being from 5 cm³ to 300 cm³. As described in more detailbelow, the geometry or shape of the removal volume, i.e., the void leftin tissue following tissue removal, will generally be spherical, ovoid,cylindrical, or other shape characterized by at least one axis ofsymmetry. The axis of symmetry will usually arise because of the mannerin which the tissue removal devices are used, as described in moredetail below.

[0015] In a first aspect, methods according to the present inventioncomprise positioning an energy conductive element at a target site intissue beneath a tissue surface. The energy conductive element isenergized and moved through successive tissue layers, where the elementis energized with sufficient energy to vaporize tissue in saidsuccessive layers. Such sequential removal of successive layers oftissues will produce a desired removal volume, typically having thegeometries and sizes set forth above.

[0016] In a second aspect, methods according to the present inventioncomprise providing an instrument having a shaft and a repositionableenergy conductive element on the shaft. The element is advanced throughthe tissue surface to a target site in solid tissue, where the elementis in a low profile configuration (e.g., radially collapsed into theshaft) and the proximal end of the shaft remains outside of the solidtissue to permit manipulation. The shaft is moved relative to the tissuesurface and the element repositioned relative to the shaft while theelement is being energized with sufficient energy to remove tissue. Thecombined movements of the shaft and the element relative to the shaftcause the element to pass through successive tissue layers at or nearthe target site and to vaporize said layers to produce the desiredremoval volume.

[0017] Usually, the methods for removing tissue as described above willfurther comprise imaging the solid tissue and positioning the energyconductive element based on the image. The imaging may be any type ofconventional, two-dimensional or three-dimensional medical imaging,including fluoroscopic imaging, ultrasonic imaging, magnetic resonanceimaging, computer-assisted tomographic imaging, optical imaging, and thelike. Positioning of the energy conductive device may be entirelymanual, where the user may view the image of the target site either inreal time, as a pre-operative image only, or a combination of real timeand pre-operative images. Alternatively, the energy conductive devicemay be automatically positioned based directly or indirectly on theimage using robotic or other automatic positioning equipment.Optionally, such automatic positioning equipment can be programmed basedon a pre-operative or real time image of the target region.

[0018] The methods of the present invention will preferably furthercomprise collecting vapors and cellular debris produced by the tissuevaporization and removing those vapors through the overlying tissue andthe tissue surface. Usually, vapor removal will comprise aspirating thevapors from the site or volume of tissue removal as the vapors are beingproduced. Usually, the vapors will be aspirated through a tissue tractbetween the tissue surface and the target site, more typically beingthrough a lumen in the shaft of the device used for removing the tissue.

[0019] The energy conductive element is moved through a pattern ofsuccessive tissue layers which, in the aggregate, will form the desiredtissue removal volume. The energy conductive element may be moved in anymanner, typically being moved by manipulation of the shaft upon which itis mounted. For example, the energy conductive element may be movedrelative to the shaft while the shaft itself is moved so that thecombined motions of the element and the shaft define the desired removalgeometry. Alternatively, the energy conductive element could be moved onthe shaft while the shaft remains stationary. In the latter case, aservo or other drive mechanism could be provided within the shaft tomove the energy conductive element through its desired pattern.

[0020] The shaft will usually be rotated and/or axially reciprocated inorder move the energy conductive element through tissue along or aboutone axis. In turn, the energy conductive element may be pivoted, bowed,or otherwise moved or deflected relative to the shaft to provide furtheraxes or dimensions of the removal volume. In a first exemplary removalmethod, a shaft having a rigid energy conductive member is introduced toan internal tissue target site with the element lying coaxial to theshaft. The shaft is then rotated and the element pivoted to provide aspherical or partial spherical tissue removal geometry. In a secondexemplary embodiment, the energy conductive element comprises one ormore flexible elements which may be bowed to form a series of arcuatetissue removal paths as the shaft is rotated. Other approaches includedisposing a lateral energy conductive element beneath tissue andsimultaneously rotating and reciprocating the support shaft so that acylindrical removal volume is formed, with the length of the cylinderdetermined by the length of reciprocation. Other combinations of motionbetween the shaft and energy conductive element may also be utilized.

[0021] The type of energy transmitted or provided through the energyconductive element will preferably provide for heating of the tissue.For example, high frequency energy, such as radiofrequency or microwaveenergy, may be delivered in a monopolar or bipolar manner to vaporizethe tissue. Typically, the radiofrequency energy will be applied with acutting waveform at a frequency in the range from 100 kHz to 2 MHz, anda current in the range from 1 mA to 50 A, 0.5 mA to 10 A, depending onsurface contact area and tissue type. Alternatively, energizing cancomprise directly heating the element, typically to a temperature in therange from 100° C. to 300° C., usually 600° C. to 2000° C. Heating ispreferably achieved using optical energy, e.g., laser energy, deliveredthrough a fiberoptic element within the energy conductive element.Alternatively, heating can be achieved using an electrical resistanceheater which comprises or is disposed within the energy conductiveelement.

[0022] The present invention further provides apparatus for removingtissue. In a first instance, a tissue ablation device comprises a shafthaving a proximal end, a distal end, and a lumen therethrough. At leastone flexible energy conductive element is disposed near the distal endof the shaft, and a means for bowing the element between a substantiallylinear profile (where the element lies directly over the shaft) and aseries of arcuate profiles spaced progressively further from the shaftis provided. The bowing means will typically include a mechanism foraxially advancing a proximal end of the flexible energy conductiveelement. By preventing or limiting axial movement of a distal end of theflexible energy conductive element, the element will be caused to bowradially outwardly in the desired arcuate configuration. Alternatively,a proximal end of the flexible energy conductive element may be fixed orlimited relative to the shaft and a rod or other device for proximallyretracting a distal end of the energy conductive element provided. Itwould further be possible to simultaneously draw both ends of theelement together. Other mechanisms, such as expandable cages, parallellinkages, shape heat memory drivers, or the like, may also be providedfor bowing the element radially outwardly. The tissue ablation devicewill further comprise an aspiration connector coupled to the lumen foraspirating vapors produced at the distal end. A power supply connectoris further provided to permit electrical coupling of the energyconductive element to a desired power supply.

[0023] The shaft of such devices may be substantially rigid, typicallyhaving a diameter in the range from 0.5 mm to 20 mm, typically 2 mm to 7mm, and a length in the range from 2 cm to 50 cm, usually 5 cm to 25 cm.The devices will also typically have a handle secured at or near theproximal end of the shaft, and at least one of the aspiration and powersupply connectors will usually be disposed on the handle. Optionally, amotor may be provided in the handle or separate from the handle to helpdrive the device. For example, the motor could be connected to rotateand/or reciprocate the shaft relative to the handle in order to drivethe device in a desired manner. Alternatively or additionally, the motorcould be connected to bow the flexible energy conductive element in acontrolled manner. In the exemplary embodiments, however, all motions ofboth the shaft and the energy conductive element will be manual.

[0024] The shaft of such devices may also be flexible, typically in theform of a catheter having a diameter in the range from 0.5 mm to 10 mm,and a length in the range from 25 cm to 250 cm. Usually, when used foraccess to natural body lumens, such as the colon, uterus, esophagus,fallopian tubes, sinuses, uterus, ureter, and the urethra, the shaftswill be introduced through or as part of an endoscope. The cuttingelements for performing the tissue removal will then be deployed from ornear the distal end of the catheter. Typically, the cutting elementswill be deployed laterally from the catheter and a stylet or otherintroducer will be utilized to permit subcutaneous introduction asrequired by the present invention. In other cases, the devices may beintroduced intravascularly, typically through the femoral or otherveins, to target organs, such as liver, kidney, prostate, lung, anduterus. The cutting elements can then be deployed from the cathetersthrough the blood vessel wall into the target organ.

[0025] The energy conductive elements may be configured to provide forany of the energy delivery modes set forth above. In particular, energyconductive elements may comprise electrodes suitable for the delivery ofhigh frequency electrical energy, typically radiofrequency energy havingthe particular frequencies and other characteristics set forth above.Alternatively, the energy conductive elements may be configured toprovide for direct heating of the elements themselves, usuallycomprising either an optical fiber for delivering light energy orcomprising an electrical resistance heater together with the necessarywiring to connect the resistance heater to a suitable power source.

[0026] The flexible energy conductive elements may take a wide varietyof forms. A first exemplary form will be a simple elastic or superelastic metal wire, typically having a diameter in the range from 0.1 mmto 5 mm, preferably from 0.5 mm to 2 mm. The wire may be formed from anysuitable material, including stainless steel, nickel titanium alloy,tungsten, or the like. The wire may be composed of single material ormay be a composite material, e.g., where a portion of the wire isselected for high electrical conductivity while another portion of thewire selected for elastic or other properties. The electricallyconductive elements may also be in the form of ribbons, i.e., having awidth substantially greater than its thickness. Such ribbon structureswill have greater mechanical rigidity when they are radially expandedthrough their narrow dimension. Often times, different types of energyconductive elements may be combined in a single device. In an exemplarydevice, a pair of wire elements are disposed on opposite sides of theshaft with a pair of ribbon elements offset by 90°. Each of the fourelements is coupled to the other so that they open and close (be “bowed”and relaxed) synchronously. Usually, such structures will be formed forbipolar operation, where the ribbon elements will have a much greatersurface area than the wire elements so that the ribbons connect as adispersible electrode, i.e., an electrode where minimum cutting takesplace. In such cases, the ribbon electrode can also serve to act as asurface coagulation electrode to help control bleeding. In someinstances, it will be desired that the wire cutting electrodes beadvanced slightly radially ahead of the ribbon electrodes. Such a designallows the ribbons to open under a spring force to “automatically”expand as the wire electrodes remove successive layers of tissue.

[0027] A second exemplary tissue ablation device comprises a shafthaving a proximal end, a distal end, and lumen therethrough. Asubstantially rigid energy conductive element is pivotally attached tothe shaft near its distal end. The device further includes a means forcausing the element to pivot, such as a push wire, pull wire, rack andpinion driver, gear driver, or the like. The device will further includeaspiration and power supply connectors, both as generally describedabove.

[0028] The nature of the shaft and the types of energy conductiveelements which may be deployed are all similar to corresponding aspectsof the first embodiment of the tissue ablation device described above.The nature of the pivotally connected energy conductive element will,however, differ. The pivotally attached energy conductive element willusually be straight, typically being in the form of a cylindrical pinhaving a length in the range from 1 mm to 75 mm, and a width or diameterin the range from 0.5 mm to 5 mm. A preferred geometry includes acircular or flat cross-section. The rigid element may be pivotallyattached near its middle, near one end thereof, or anywhere else alongits length. In an illustration example, the element is pivotallyattached near its middle in order to effect a spherical tissue removalvolume as the device is rotated and the pin pivoted through 90° or more,as described in detail below.

[0029] The present invention still further provides kits comprising adevice having an energy conductive element which is connectable to apower supply and which provides energy sufficient to vaporize successivelayers of tissue as the element is moved therethrough. The device mayhave any of the configurations described above. The kit will furthercomprise instructions for use setting forth a method as in any of themethods described above. Typically, at least the device will be presentin a sterile package, and the instructions for use may printed on aportion of the package or may be on a separate instruction sheetaccompanying the package. Suitable packages include pouches, trays,boxes, tubes, or the like. Suitable sterilization techniques includegamma radiation, ethylene oxide treatment, or the like.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030]FIG. 1 illustrates a perspective view of a first apparatusconstructed in accordance with the principles of the present invention.

[0031]FIG. 2A-2E illustrate use of the apparatus of FIG. 1 in performinga method according to the principles of the present invention.

[0032]FIGS. 3A and 3B illustrate use of the apparatus in FIG. 1 inperforming an alternative embodiment of the method of the presentinvention.

[0033]FIG. 4 illustrates a second apparatus constructed in accordancewith the principles of the present invention.

[0034]FIG. 5 is a detailed view of the distal end of the apparatus ofFIG. 1, shown in section.

[0035] FIGS. 6A-6D illustrate use of the apparatus of FIGS. 4 and 5 inperforming a method in accordance with the principles of the presentinvention.

[0036]FIGS. 7A and 7B illustrate a third alternative construction forapparatus in accordance with the principles of the present invention.

[0037]FIG. 8 is a cross-sectional view taken along line 8-8 of FIG. 7A.

[0038]FIGS. 9A and 9B are alternative cross-sectional views taken alongline 9-9 of FIG. 7B.

[0039]FIG. 10 illustrates an alternative construction for a ribbonelectrode according to the principles of the present invention.

[0040]FIG. 11 illustrates a fourth alternative embodiment of theapparatus of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0041] Referring now to FIG. 1, a tissue ablation device 10 comprises ashaft 12 having a distal end 14 and a proximal end 16. An energyconductive element 18, typically a rigid cylindrical electrode or pin,is pivotally attached at point 19 to the distal end of the shaft 12.Handle 20 is connected to the proximal end 16 of the shaft, and a leadscrew 22 is provided near a distal end of the handle to cause pivotingof the element 18 and/or rotation of the shaft 12 relative to thehandle. Usually, the lead screw 20 is coupled to the pivoting element 18through a push/pull wire 21 which passes through the shaft 12 andemerges near the distal end 14 thereof. The push/pull wire 21 is shownto be attached near an outer end of the element 18, it could of coursebe connected much more closely to the pivot pin. Moreover, numerousother pivoting mechanisms could be provided, as described above.

[0042] Referring now to FIGS. 2A-2E, use of the tissue ablation anddevice 10 to vaporize and remove a target region TR of tissue T beneatha tissue surface TS will be described. Initially, the device 10 isconnected to an electrosurgical power supply through connector cable 26.The electrosurgical power supply, typically operating at a frequency inthe range from 100 kHz to 2 MHz, with conventional sinusoidal ornon-sinusoidal waveforms. Preferably, the power supply will be set toprovide a cutting waveform at a power level within the ranges set forthpreviously. Suitable power supplies are available from commercialsuppliers, such as Valleylabs, Aspen, Bovie, and Birtcher. Afterconnection, the energy conductive element 18 will be axially alignedwith the shaft and penetrated beneath the tissue surface, as illustratedin FIG. 2A. Optionally, the radiofrequency current may be appliedthrough the element 18 to facilitate the initial penetration. With theembodiment of FIG. 1, the device will usually be operated in a monopolarfashion with one pole of the power supply being connected to the element18 and a second pole being connected to a dispersive electrode which isattached to the exterior patient's skin, typically in the lower backarea. In some instances, the device of FIG. 1 can be provided withbipolar elements 18, e.g., with a pair of conductive stripes formed onthe element, in order to permit bipolar operation, i.e., where bothpoles of the electrosurgical power supply are connected to the stripeson the element. Moreover, while the cutting current will usually beapplied with a cutting waveform during tissue removal, at other timesduring the process it may be desirable to coagulate the tissue byapplying a coagulation waveform. This can be done at the end of thecutting procedure, when some instances may be performed in alternativecycles with the cutting process in order to inhibit excessive bleedingduring the operation.

[0043] After the device 10 is initially positioned, as shown in FIG. 2A,the shaft 12 will be rotated and the element 18 pivoted in the directionof the arrows shown in FIG. 2B. The result is a void or cavity V beingformed in the solid tissue with an initial geometry comprising a pair ofcones joined at their apices. As the shaft 12 continues to be rotatedand the energy conductive element 18 continues to be pivoted in thedirection of the arrows, the two cones will grow until they join into agenerally spherical void V, as shown in FIG. 2C. After the sphericalvoid is completed, the element 18 may be returned to its coaxialconfiguration, and the shaft 12 and element 18 is withdrawn, leaving thevoid V intact at the end of a closed tissue tract TT, as illustrated inFIG. 2D.

[0044] The use of radio or other high frequency electrical energy ispreferred for forming the tissue void as just described. Theradiofrequency energy will not only vaporize tissue, permitting theresulting vapors to be withdrawn through the lumen of the shaft 12(typically by connecting aspiration port 24 to a suitable vacuumsource), but also cauterize the inner surface of the void as it is beingformed. Such cauterization, in turn, limits or controls bleeding as thetissue is being removed. After the removal is complete, it may bedesirable to introduce collagen, gelatin, autologous tissue, or otherbiologically compatible tissue fillers into the void region to inhibittissue collapse, further control bleeding, deliver drugs (which may beincorporated into such matrices), or the like.

[0045] Alternatively, after a tissue void has been created, the void cansimply be collapsed in order to “debulk” a tissue region. For example,for the treatment of benign prostate hyperplasia, it may desirable toremove a small volume of tissue and thereafter collapse the tissue torelease pressure on the urethra. Optionally, a tissue glue, sealant, orother material, may be introduced after the tissue void has beencollapsed in order to maintain the collapsed configuration.

[0046] Referring now to FIGS. 3A and 3B, the device 10 could be utilizedin other specific treatment protocols. For example, as illustrated inFIG. 3A, the device 10 may be introduced so that energy conductiveelement 18 on shaft 12 is initially pivoted at 90° so that it liestransversely with respect to the axis of shaft 12. Shaft 12 may then beaxially reciprocated in the direction of arrow 30. Initially, arelatively flat layer of tissue 32, as shown in broken line, will beremoved with the reciprocation. By then slowly rotating the shaft 12, asshown by arrow 34, and continuing to reciprocate the shaft in thedirection of arrow 30, the removed tissue volume will grow to have anhourglass-shaped cross-section, as shown in broken line pattern 36 inFIG. 3B. It will be appreciated that rotation may be continued until afull cylindrical tissue removal volume is achieved. As a furtheralternative, it will be appreciated that the speed of rotation of shaft12 may be increased relative to the speed of reciprocation so that thecylinder is formed as a series of circular or disc-shaped removalvolumes which are in turn “stacked” over one another as the shaft isaxially advanced in one direction only (the element 18 would cut throughthe tissue in a “propeller-like” fashion).

[0047] Referring now to FIGS. 4 and 5, a second embodiment of the tissueablation device of the present invention will be described. Tissueablation device 40 comprises a shaft 42 having a distal end 44 andproximal end 46. A handle 48 is attached to the proximal end of theshaft 46, and an aspiration connector 50 and power supply connector 52,are further provided, generally as described in connection with thefirst tissue ablation device 10.

[0048] An energy conductive element 50 provided in device 40, however,differs from that described with respect to device 10. In particular, aflexible energy conductive device 50, typically in the form of anelastic wire, is provided so that it can emerge radially outwardly froma slot 52 formed near the distal end 44 of the shaft 42. The wire 50 maybe bowed outwardly by advancing a proximal portion of the wire 50 in adistal direction, as shown by arrow 56. It will be appreciated that thewire will assume an arcuate configuration, and that the degree to whichthe arc extends radially outward from the shaft will depend on how farthe proximal end has been distally advanced. The wire 50 will be coupledto a suitable energy source through power supply connector 52, typicallyto a radiofrequency power supply.

[0049] Use of the device 40 is illustrated in FIGS. 6A-6D. Device 10 isinitially introduced so that distal end 44 of shaft 42 lies at or near atarget region TR in tissue T beneath tissue surface TS. Treatment thencommences by energizing the wire 50, advancing the wire 50 radiallyoutward, as shown by the arrow in FIG. 6B, and rotating the shaft 42 asshown by the second arrow in FIG. 6B. It will be appreciated that thewire moves outwardly in a generally spiral pattern as the shaft isrotated and successively removes layers of the tissue to form a void Vhaving a generally ovoid pattern, shown at its initial stages in FIG.6B. As the wire 50 advances further outwardly, the ovoid shape of a voidV becomes closer to spherical, as shown in FIG. 6C. At the end of thetreatment, the void V will typically have a full sphericalconfiguration, as shown in FIG. 6D. It would be possible, of course, tostill further advance the wire 50 so that the void becomes increasinglylarge in its lateral dimension, thus becoming a flattened sphere. Theability to further extend the sphere, however, may be limited by themechanical characteristics of the element 50 being rotated. The innersurface of void V will be cauterized in order to control bleeding,generally as described above in connection with the use of device 10.Moreover, the void V can optionally be filled with collagen, gelatin, orother tissue-filling materials, also as generally described above inconnection with the first embodiment.

[0050] Referring now to FIGS. 7A and 7B, a further alternativeembodiment for an energy conductive element array for use in devicesconstructed in accordance with the principles of the present inventionwill be described. Conductive element array 60 comprises a pair ofdiametrically opposed wire electrodes 62 and a pair of diametricallyopposed ribbon electrodes 64. The electrodes 62 and 64 are attached to adistal end of shaft 68, and a central pull wire 70 is attached to adistal tip 72. By proximally advancing the pull bar 70 in the directionof arrow 74 (FIG. 7B), the tip 72 is drawn proximally, axiallycompressing the electrodes 62 and 64, causing them to expand radiallyoutwardly. (The relationship between the electrodes 62 and 64 and thepull wire 70 is best shown in FIG. 8.) Usually, the wire electrodes 62and ribbon electrodes 64 will advance radially outwardly at the samerate so that they lie at the same radial distance from the shaft 68, asillustrated in FIG. 9. In some instances, however, it will be desirableto have the wire electrodes 62 advance ahead of the ribbon electrodes64, as illustrated in FIG. 9B. This will be a particular advantage whenthe device is driven in a bipolar fashion, with wires 62 driven at anopposite polarity from ribbon 64. Since the ribbons have a substantiallygreater surface area, they will act dispersive electrodes, while thewire electrodes 62 act as the cutting electrodes. By having the outersurfaces of the ribbon electrodes “trailing” the radially advancing wireelectrodes 62, the ribbon electrodes can better act to cauterize thetissue surface which is being created.

[0051] Ribbon electrodes can also be used by themselves, eithersingularly or in multiplies, in the devices and methods of the presentapplication. In particular, a ribbon electrode having thecross-sectional configuration shown in FIG. 10 could be used for bothcutting and cauterization in a bowed electrode device. Ribbon electrode80 would have an electrically non-conductive core 82 and electricallyconnective cutting surfaces 84 and 86 formed on the leading edgesthereof. One or more cauterizing electrodes 88 would be formed on eitheror both of the major surfaces of the core 82. This way, the electrode 80could be driven so that either of the surfaces 84 and 86 initiallyengage tissue with radiofrequency energy having a cutting waveform.Simultaneously, or on a subsequent passage of the electrode 80,radiofrequency energy having a coagulation waveform could be applied tothe newly created tissue surface using the electrode surfaces 88.

[0052] A further embodiment of an energy conductive element array 100constructed in accordance with the principles of the present inventionis illustrated in FIG. 11. The array includes a plurality of ribbonelectrodes 102, optionally being in the form of electrodes 80 (FIG. 10),which are connected at their proximal ends 104 to the distal end of theouter shaft 106. The distal ends 108 of the elements 102, in turn, areconnected to an end cap 110 secured at the distal end of an inner shaft120. The inner shaft 120 has a lumen which opens into an open chamber122 formed in the distal end of the shaft 120. The opening 122 issuitable for collecting the vapor and cellular debris which is releasedduring the tissue vaporization methods described herein. The elements102 may be radially expanded and contracted by axially reciprocating theinner shaft 120 with respect to the outer shaft 106. The embodiment ofFIG. 11 could be further modified to include only a single wireelectrode and three ribbon electrodes (not shown). During cutting, thewire electrode could be powered and the three ribbon electrodes act aspassive electrodes. During a subsequent coagulation step, the cuttingwire electrode could be de-energized, the coagulation power applied toone of three ribbons, with the other two ribbons acting as passiveelectrodes. In order to enhance performance, the ribbon electrodethrough which the coagulation power is applied could have a smaller areathan the two passive ribbon electrodes.

[0053] While the above is a complete description of the preferredembodiments of the invention, various alternatives, modifications, andequivalents may be used. Therefore, the above description should not betaken as limiting the scope of the invention which is defined by theappended claims.

What is claimed is:
 1. A tissue ablation device comprising: a shafthaving a proximal end, a distal end, and a lumen therethrough; at leastone flexible energy conductive element disposed near the distal end ofthe shaft; means for bowing the element between a substantially linearprofile where the element lies directly over the shaft and a series ofarcuate profiles spaced progressively away from the shaft; an aspirationconnector coupled to the lumen near the proximal end of the shaft; and apower supply connector disposed near the proximal end of the shaft andelectrically coupled to the energy conductive element.
 2. A device as inclaim 1, wherein the shaft is substantially rigid.
 3. A device as inclaim 2 or 3, wherein the shaft has a diameter in the range from 0.1 mmto 20 mm and a length in the range from 0.5 cm to 50 cm.
 4. A device asin claim 3, wherein the shaft is flexible and has a length in the rangefrom 25 cm to 250 cm.
 5. A device as in claim 1, further comprising ahandle secured to the proximal end of the shaft.
 6. A device as in claim5, wherein the aspiration connector and/or the power supply connectorare disposed on the handle.
 7. A device as in claim 1, furthercomprising a motor attachable to the proximal end of the shaft.
 8. Adevice as in claim 7, wherein the motor is attached to both rotate theshaft and move the energy conductive element relative to the shaft.
 9. Adevice as in claim 1, wherein the energy conductive element comprises anelectrode which conducts high frequency electrical energy.
 10. A deviceas in claim 1, wherein the energy conductive element comprises a heatingelement.
 11. A device as in claim 10, wherein the heating elementcomprises an optical fiber for delivering light energy to heat theenergy conductive element.
 12. A device as in claim 10, wherein theheating element comprises an electrical resistance heater.
 13. A deviceas in claim 1, wherein the energy conductive element comprises a wire.14. A device as in claim 1, wherein the element comprises a ribbon. 15.A device as in claim 1, comprising at least two or more energyconductive electrodes, wherein the bowing means is adapted to bow theelements at substantially the same rate.
 16. A device as in claim 1,comprising at least one wire electrode and at least one ribbonelectrode, wherein the electrical connector provides for connecting thewire and ribbon electrodes to opposite poles of a high frequencyelectrical power supply.
 17. A device as in claim 16, wherein the bowingmeans advances the wire electrodes radially ahead of the ribbonelectrodes.